Tube Colors & General Use
What color tube is commonly used for a Complete Blood Count (CBC)?
Lavender (or Purple)
What is the full name of the additive found in lavender-top tubes?
Ethylenediaminetetraacetic acid (EDTA)
What is the primary function of a clot activator in a red-top tube?
To accelerate the clotting process
What is the anticoagulant found in light-blue-top tubes?
Sodium citrate.
What type of tube is used for trace metal analysis, and what is a key characteristic of this tube?
Royal blue-top tube. It is trace element-free.
What color tube is typically used for coagulation studies, such as PT and PTT?
Light Blue
How does EDTA prevent blood clotting?
By binding to calcium, which is essential for the coagulation cascade.
What is the purpose of the gel separator in a gold-top (SST) tube?
To create a barrier between the serum and the blood cells after centrifugation.
How does heparin prevent blood clotting?
By inhibiting thrombin, a key enzyme in the coagulation cascade.
What is the additive in a yellow-top (SPS) tube, and what is it used for?
Sodium polyanethole sulfonate (SPS). It is used for blood cultures.
What color tubes are used to obtain serum, and what general type of testing is performed on serum?
Red or Gold. General type of testing is chemistry, immunology, and serology.
What is the primary difference in testing performed using a pink-top tube compared to a lavender-top tube?
Pink-top tubes are primarily used for blood banking and compatibility testing, while lavender-top tubes are used for hematology tests like CBCs.
What type of sample is obtained from red, gold, or orange-top tubes after centrifugation?
Serum.
What is the anticoagulant found in gray-top tubes, and what other additive is also present in these tubes?
Potassium oxalate, and sodium fluoride.
What is the purpose of ACD (acid citrate dextrose) as an additive, and what type of testing is it used for?
It acts as an anticoagulant and preservative. It is used for DNA testing and blood banking procedures.
What color tube is used for glucose testing and lactate measurements?
Gray
Why is it crucial to ensure a full draw in EDTA tubes?
An incorrect blood-to-additive ratio can affect cell morphology and lead to inaccurate test results.
What are some common types of tests performed on serum?
Chemistry panels, liver function tests, lipid panels, and some immunology tests.
What is the specific mechanism by which sodium citrate prevents coagulation?
It binds to calcium ions, preventing them from participating in the clotting process.
What are the purpose and use of a tube containing thrombin?
Thrombin is a rapid clot activator. Used when a very fast serum seperation is needed, such as in STAT chemistry testing.
What color tube or bottle is used for blood cultures, and what is its purpose?
Yellow (SPS) or blood culture bottles. Its purpose is to detect the presence of microorganisms in the blood.
What specific types of tests are performed on a lavender top tube?
Complete Blood Count (CBC), Erythrocyte Sedimentation Rate (ESR), Hemoglobin A1c (HbA1c), and Reticulocyte count.
Explain the difference between a red-top plastic tube and a gold-top (SST) tube in terms of their additives and the resulting sample.
Both contain clot activators, but gold-top tubes also contain a gel separator. Red-top tubes yield serum that may contain some cellular components, while gold-top tubes produce serum that is separated from the cells by the gel barrier.
Compare and contrast the mechanisms of action and common uses of heparin and EDTA as anticoagulants.
Explain the purpose and use of a tube containing a protease inhibitor.
Protease inhibitors prevent the breakdown of certain proteins. Used for specialized tests where protein stability is crucial, such as some plasma protein assays.